Technical Field
The present invention relates to a high-sound-absorption composite material based on an expanded polytetrafluoroethylene microporous membrane and the modified membrane thereof coated on the surface for the traffic sound barrier and a preparation method thereof.
Description of Related Art
In the design of sound barriers, wind load on viaducts, expressways, urban light rail and metros, the collision safety of traffic vehicles and all-weather outdoor corrosion resistance have been taken into full consideration. The sound barrier with a good-looking appearance has a long service life and is a universal sound isolation and reduction facility in modern cities. Sound waves generate reflection, transmission and diffraction when reaching a sound barrier during spreading. The sound barrier with a height in the range of 1 m-5 m achieves an average noise reduction of 10-15 dB (A) (125 Hz-40,000 Hz, 1/3 octave) in an effective area. The noise source of the high speed rail or metro or expressway reaches approximately 100 dB when a high-speed train runs at a speed of 250-350 KM/H or when an overhead highway bears a large traffic flow. The noises reduced and isolated by the sound barrier still reach 85 dB within 100 m of the sound source, failing to reach the limit in the environmental noises, 60-75 dB, which does not affect working and living.
However, various organic or inorganic fibers with a fiber aggregate structure and products thereof, porous-holed foamed plastics and expanded perlite products, glass wool and mineral wool with a great amount of mutually-connected open micropores or various sound-absorption plates or sound-absorption components mainly from the mentioned glass wool and mineral wool are not resistant to the outdoor environmental climate; in particular, the outdoor ultraviolet radiation speeds up aging of the above mentioned materials and shortens their service life; after three years, those materials are aged to be cracking or powdery, losing the sound-absorption function and damaging the good-looking appearance. Thus, the application of the above mentioned materials in the sound barrier project is limited.